years = [2023, 2022, 2021, 2020]
cities = ["呼和浩特", "包头", "鄂尔多斯"]
# 对应三个城市的常住人口（单位：万人）
popu = [346, 230, 220]
for i in range(len(years)):
    year = years[i]
    print(f"--- {year}年人口数据 ---")
    for j in range(len(cities)):
        print(f"{cities[j]}市人口: {popu[j]}万人")

